Sonny Bill Williams was reported on Sunday to be on the verge of dumping the rugby union world champion All Blacks in favour of a lucrative contract in Japan before returning to rugby league in Australia. The New Zealand Rugby Union (NZRU) would only confirm Williams would hold a media conference on Monday with his rugby union mentor Wayne Smith at his side. League convert Williams has been the centre of speculation for months about his playing future after signing only a one-year deal with the NZRU following the All Blacks 8-7 victory over France in the World Cup final last October. New Zealand newspapers have reported Williams is now ready to announce a deal to move to Japan for one season with the Panasonic club before signing on with the Sydney Roosters in the Australian National Rugby League competition. He is tipped to earn in excess of $1.4 million for about 10 weeks in Japan and $570,000 to join the Roosters with the potential to earn much more from his professional boxing career, which will continue along with the rugby. Williams, who starred for the All Blacks in their recent three-Test series clean sweep of Ireland, was declared unavailable to meet the media after his Chiefs side lost to the Crusaders 28-21 in Friday night\'s Super rugby match. Confirmation of a move to Japan before returning to rugby league would likely rule Williams out of the All Blacks squad for the upcoming Rugby Championship, which also involves South Africa, Australia and Argentina. The 26-year-old Williams walked away from a world-record $5.0 million offer from French club Toulon to return to New Zealand in 2010 to join the Crusaders in a bid to make the All Blacks World Cup side. This year he moved to the Chiefs, following his mentor Smith to the franchise, after the former All Blacks assistant coach played a significant role in developing Williams as a leading rugby union midfield back.